Westinghouse Electric Company, United States

Linking the 3D model to the schedule saves time and money before construction even begins

Nuclear power is safe,
clean and vital to a balanced energy supply to meet the world's growing need for
electricity. The improved performance, reliability, and efficiency of present-day
nuclear power plants have sparked new interest in plant construction. However,
the industry must take a greater role in lowering new power plant construction costs.

Enter the AP600, a
600-megawatt advanced pressurized light-water reactor plant developed jointly by
Westinghouse, its subcontractors and contributors, the U.S. Department of Energy
and the Electric Power Research Institute (EPRI).

The AP600 project
focuses on reducing two of the top contributors to power plant construction cost: financing
during construction and onsite skilled craft labor. By using modular
construction methods, Westinghouse and its project partners found that the AP600
- and its larger successor, the AP1000 - can be built in 36 months, from the
first concrete pour to fuel loading. This is one-fourth to one-half the
construction time of the most recent nuclear plants in the United
States.

To ensure the 36-month
timeframe could be met, EPRI suggested that Westinghouse investigate the "4D"
concept, which involves visually linking specific parts of the 3D plant model to
its related installation activities. Intergraph provided the core plant modeling software for the
virtual construction project: PDS®, SmartPlant® Review and FrameWorks®
Plus.

The AP600 project team
not only verified the schedule through visualization, but it found another three
to five months could be eliminated through logic and design changes alone. This
has a significant positive impact on financing costs.

"Building a nuclear
plant is extremely capital intensive," says Ed
Cummins, Westinghouse's director
of passive plant development. "Cutting
down construction time greatly reduces
investment costs. Not tying up
roughly $1 billion for an extra four months adds
up to significant
improvements in power plant construction cost. The plant also can begin operating and
generating
income sooner, contributing to the economic benefits."

Shortening the
construction cycle

One of the more
dramatic schedule opportunities that was found during the electric plant engineering involved reinforcing bars,
commonly known as rebar. During a visualization exercise involving the AP600
critical path, something hidden in 300 sheets of written activity reports became
obvious. For virtually weeks, nothing was happening on the nuclear island. When
activity finally continued, it was clear that the delay was tied to some rebar,
which had to be placed after the containment vessel head was
installed.

Alternatives were
quickly researched. Westinghouse found that the rebar could be included in the
containment vessel head before placing the structure in the plant. This could be
done in the yard with no negative impacts. The crane could still lift the
structure, and the design remained robust.

The change was made in
the model and it immediately shortened activities by a full month. This not only
addressed the first objective of reducing the nuclear plant construction cycle, but it also
demonstrated the value of visualization.

Considering that
indirect power plant construction costs - leases, taxes, insurance, interest and the like -
for this project will be about $70,000 per day, this one change will save about
$2 million. This is an incredible return on the visualization effort. The
power plant design software paid for itself right then.